Three Part Question

Does [pleurotomy] during [IMA harvest] increase the incidence of [post-operative pulmonary complications]?

Clinical Scenario

You are a first year cardiothoracic registrar who is starting to work for a consultant surgeon who always prefers the pleura to remain intact whilst harvesting the internal mammary artery (IMA). The surgeon avoids pleurotomy to reduce pulmonary complications after cardiac surgery, but you wonder whether there is any evidence in the literature to support this practice

Search Strategy

Medline 1966-Oct 2004 using the OVID interface.
[cardiac surgery.mp OR CABG.mp OR coronary art$ bypass graft$.mp OR cardiopulmonary bypass.mp OR exp cardiovascular surgical procedures/ OR heart surgery.mp OR LIMA.mp] AND [exp Pleura/ OR Pleura$.mp OR extrapleur$.mp OR pleurotomy.mp]

Search Outcome

One hundred and fifty-four papers were found of which 19 were relevant. Eleven papers were discounted as they did not compare IMA harvest with intact pleura versus IMA harvest with open pleura, and thus did not directly address the question. There were no meta-analyses on this topic. Three RCTs were identified and the remainder were all cohort studies with small sample/population sizes. These are presented in the table

EF <30% excluded
12 in group I with repair of pleura
Decision to skeletonize IMA based on surgeon's experience
If there were small breaches of the pleura these were repaired and included in group I
Analysis only for surviving patients; 2 died in group I, 7 in II, 1 in III

Comment(s)

The majority of relevant studies assessed the effect of pleurotomy on post-operative lung function, ventilatory requirements and radiographic changes. Only three studies considered the effect of pleurotomy on clinical outcome [Norea, Lim and Ali et al]. In addition, the lengths of post-operative follow-up varied extensively from 30 min to 3 months. We identified three PRCTs that compared IMA plus pleurotomy to IMA without pleurotomy.
The largest PRCT was conducted by Noera et al, the only significant outcome being greater transfusion requirements in the pleurotomy group, although they did find that the rate of pleural effusion and raised left hemidiaphragm was greater albeit not significant in the same group. This study is further supported by Ali et al and Wimmer-Greinecker et al. In the study undertaken by Ali et al., they found that the pleurotomy group had significantly more pleural effusions but that this did not result in more thoracocenteses. Pleurotomy also safe-guarded against the development of cardiac tamponade, with 5 in the closed group but none in the open pleura group. Another clinically relevant outcome was that hospital stay was not different between the two groups.
Lim et al assessed post operative chest radiology and length of stay in a heterogeneous group that comprised 138 CABG, 39 valve replacements and 29 CABG + valve replacement. Patients were divided into those with pleurotomy(n=164) and those without (n=42). The pleurotomy group had significantly more atelectasis (67.7% vs. 45.2%, P<0.007) but there was no difference in rates of consolidation, effusion or length of stay.
In a relatively small study, Rolla et al recruited 57 patients all of whom had an IMA conduit, therefore blinding chest radiograph reporting. The two groups were of similar size, 32 with pleurotomy, 25 without. There was no difference in post-op chest radiograph on day 2 or 6 and all patients were found to have significantly worse PFTs persisting at 2 months post operation.
Tomita et al divided 99 elective CABG cases into 45 BIMA + pleurotomy, 45 IMA + pleurotomy and 9 IMA/SVG only with no pleurotomy and studied PFTs and post-operative chest radiograph changes. There were no differences between groups with all patients suffering significant reductions in PFTs.

Clinical Bottom Line

All patients undergoing cardiac surgery suffer a significant deterioration in Pulmonary Function tests and chest radiograph appearance post-operatively. Pleurotomy seems to compound this with increased rates of atelectasis and pleural effusions, although no impact on clinical outcome or length of hospital stay has been demonstrated.